US5022434A - Directional control valve - Google Patents

Directional control valve Download PDF

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Publication number
US5022434A
US5022434A US07/469,187 US46918790A US5022434A US 5022434 A US5022434 A US 5022434A US 46918790 A US46918790 A US 46918790A US 5022434 A US5022434 A US 5022434A
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US
United States
Prior art keywords
inlet
passages
reservoir
outlet
plunger
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US07/469,187
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English (en)
Inventor
Toshiaki Tsukimoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shibaura Machine Co Ltd
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Toshiba Machine Co Ltd
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Publication date
Application filed by Toshiba Machine Co Ltd filed Critical Toshiba Machine Co Ltd
Assigned to TOSHIBA MACHINE CO., LTD. reassignment TOSHIBA MACHINE CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: TSUKIMOTO, TOSHIAKI
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/8667—Reciprocating valve
    • Y10T137/86694—Piston valve
    • Y10T137/86702—With internal flow passage
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass
    • Y10T137/87185—Controlled by supply or exhaust valve
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87233—Biased exhaust valve
    • Y10T137/87241—Biased closed

Definitions

  • This invention relates to a directional control valve for controlling a drive mechanism and a direction of fluid flows in a construction equipment (specially a hydraulic shovel), particularly to the directional control valve with a regeneration function and an exhausted fluid reducing function.
  • a hydraulic circuit for a hydraulic shovel is arranged such that pressurized fluid flows discharged from two hydraulic pumps 150 and 152 are respectively entered to combined control valves 154 and 156, each of which comprises directional control valves 158, 160, 162, 164, 166 and 168, so as to respectively operate corresponding actuators such as an arm cylinder 170, a swivel motor 172, a left-traveling motor 174, a right-traveling motor 176, a boom cylinder 178 and a bucket cylinder 180.
  • actuators such as an arm cylinder 170, a swivel motor 172, a left-traveling motor 174, a right-traveling motor 176, a boom cylinder 178 and a bucket cylinder 180.
  • the arm cylinder 170, the boom cylinder 178 and the bucket cylinder 180 respectively suffer from some drawbacks due to vacuum being often generated by a downward overload which is imposed on the tensive side thereof, resulting in occurrence of cavitation in the flow passages.
  • the respective directional control valves 158, 166 and 168 for the cylinders 170, 178 and 180 are added regeneration functions whereby a pressure loss on the supply-side is compensated by bypassing fluid on the return-side to the supply-side (the hydraulic circuit of this type is hereinafter referred to as a regeneration path).
  • exhausted fluid reducing function is also added to the directional control valves so as to control a drop speed of the actuator when it is subjected to the downward overload.
  • FIG. 4(a) shows the directional control valve according to the Japanese Patent Publication No. 46-15059.
  • a plunger 50 inserted into a plunger bore 52 of a housing is reciprocated from a neutral position to left and right positions in the bore so that a cylinder can operate to start and stop a vertical motion of an actuator cylinder on which a downward load is imposed.
  • Chambers 54, 56, 58, 60, 62, 64 and 66 are located in a sequentially spaced from the right to the left in the axial direction of the plunger 50.
  • the chambers 56 and 64 are respectively connected to chambers 70a and 70b of a cylinder 70 while the chambers 54 and 66 are respectively connected to reservoirs 68.
  • a pair of annular peripheral grooves 72 and 73 are provided at the center of the plunger 50 and isolated from each other by a plunger land 28.
  • Plunger lands 79 and 80 are also formed on both end portions of the plunger.
  • An axial inner bore of the plunger 50 receives a pair of poppet valves comprising a check valve 112 and a control valve 114, a bypass valve 98 and a check valve 92 for preventing a load-drop .
  • These valves have a restoring force due to elasticity of springs being used together with the valves.
  • the supply passage 99 is communicated through a fluid passage 88 formed on the plunger side wall, with a bore 82 formed on the head side of the check valve 92 which is arranged on the left side of the axial inner bore of the plunger 50.
  • a fluid passage 88 formed on the plunger side wall with a bore 82 formed on the head side of the check valve 92 which is arranged on the left side of the axial inner bore of the plunger 50.
  • a piston 71 tends to be lowered at higher speed exceeding a capacity of the pump 128 by which the fluid is filled in a cavity of the cylinder head side chamber 70a, so that the feeding pressure of the pump is spontaneously decreased.
  • a back pressure developed in a return path through which the return flow passes is exerted on the valve head 120 of the check valve 112.
  • the back pressure is also exerted on the bypass valve 98 and serves to release the bypass valve 98 from a valve seat face so that a regeneration path can be opened.
  • FIG. 4(b) shows the directional control valve according to the Japanese Patent Publication No. 41-10446.
  • a plunger 119 Slidably inserted into a bore of the valve body 51 is a plunger 119 which can reciprocate from a neutral position to two opposite positions thereto.
  • the plunger 119 When the plunger 119 is moved to either one position, either one of central passages 67 and 69 is closed so that fluid pumped from a pump 65 is transmitted to either one of intake passages 74 and 76 through a supply passage 75 and a V-shaped connection passage 81.
  • the intake passages 74 and 76 are respectively connected to chambers 70a and 70b of the cylinder 70 through connection ports 55 and 57.
  • V-shaped connection passage 81 End portions of the V-shaped connection passage 81 are respectively communicated with a pair of peripheral grooves 83 and 91 formed outside the central passages 67 and 69 which are intersectionally communicated with a central portion of the bore in the valve body 51.
  • the V-shaped connection passage 81 is communicated with the supply passage 75 through a back pressure check valve 85.
  • a pair of another peripheral grooves 86 and 87 are formed outside the peripheral grooves 83 and 91 in the longitudinal direction of the plunger 119 and communicate with the intake passages 74 and 76.
  • an exhaust passage 103 communicating with a reservoir 68 is formed in the central portion of the valve body 51 and communicated with a U-shaped return passage 89 extending through a relief valve 130 in two opposite directions. End portions 93 and 95 of the U-shaped return passage 89 respectively are formed on the positions outside and adjacent to the peripheral grooves 86 and 87 in the longitudinal direction of the plunger 119 and intersect the bore in which the plunger 119 is reciprocated.
  • the exhaust passage 103 and the U-shaped return passage 89 communicate with each other through the relief valve 130.
  • end portions 93 and 95 of the U-shaped return passage 89 are respectively communicated through the bore in the valve body with extensions 101 and 102 extending in parallel with the intake passages 74 and 76 which are respectively connected to the connection ports 55 and 57.
  • the extensions 101 and 102 are respectively communicated with the intake passage 74 and 76 through bypasses 97 and 100 and cavity control valves 105 and 107 having the same structure as the relief valve 130.
  • the respective poppet valves are controlled such that a constant pressure difference can be maintained between the intake passages 74 and 76 and the U-shaped return passage 89. Under this operating condition, the poppet valve is separated further from the valve seat in case of reduction of the pressure in the intake passage 74 or 76.
  • the directional control valve with a regeneration path.
  • FIGS. 5(a) and 5(b) show a directional control valve with exhausted fluid throttling function.
  • the directional control valve 132 in order to control gravitational drop speed when a load "W" is vertically imposed on a cylinder rod, the directional control valve 132 is provided with an exhausted fluid throttling device 133 with a check valve, which can reduce the fluid to be exhausted from the head side chamber 70a of the cylinder 70.
  • Exhausted fluid in the head side chamber 70a of the cylinder 70 can be throttled by contracting the volume of the metering notch in the vicinity of a piston stroke end when moving the plunger.
  • the plunger is provided with a plurality of poppet valves. Therefore, a strength of the plunger may be reduced when efficiently forming a plurality of the passages in the plunger bore. Otherwise, even though the strength of the plunger is increased, the passages cannot be efficiently arranged and the manufacturing structure of the plunger may become complicated.
  • a conventional directional control valve with an exhausted fluid throttling function shown in FIG. 5(a) is provided in the outside position of the housing, with an exhausted fluid throttling device including a check valve.
  • an exhausted fluid throttling device including a check valve.
  • another conventional directional control valve includes the plunger with the metering notch so as to throttle the exhausted fluid by changing the volume of the metering notch as moving the plunger.
  • the directional control valve can effect space-saving and lower cost.
  • a variety of the plunger should be employed according to gravitational drop speed of actuators to be used and should be manufactured on the basis of configuration of the metering notch.
  • a directional control valve in combination of a casing containing a bore, a pair of inlet/outlet passages, a U-shaped supply passage formed between the inlet/outlet passages, a pair of reservoir passages formed outside the respective inlet/outlet passages, a plunger being reciprocatable in the bore and being capable of opening and closing the respective passages, so that fluid can be supplied and exhausted from inlet/outlet apertures connected to the inlet/outlet passages according to a motion of the plunger.
  • the directional control valve according to the invention is also provided with a sub-reservoir between one of a pair of the inlet/outlet passages and one of the reservoir passages such that exhausted fluid can be transmitted from the sub-reservoir to the other passage of the inlet/outlet passages when moving the plunger from the inlet/outlet aperture side to the outlet aperture side.
  • a valve body communicating with the sub-reservoir may be provided in the vicinity of the plunger.
  • the valve body is provided on one end thereof with a back pressure valve communicating with a reservoir and provided on the other end with a check valve which operates so as to transmit the exhausted fluid from the sub-reservoir to the other passage of the inlet/outlet passages when moving the plunger from the inlet/outlet aperture side to the outlet aperture side.
  • the sub-reservoir between one of a pair of the inlet/outlet passages and one of the reservoir passages, a check valve on one end of a plunger bore and a back pressure valve on the sub-reservoir, which is communicated with the reservoir.
  • a portion of the exhausted fluid can be transmitted from the sub-reservoir through the back pressure valve to the other passage of the inlet/outlet passages when moving the plunger from the inlet/outlet aperture side to the outlet aperture side.
  • a throttle valve communicating with the reservoir may be arranged on the sub-reservoir which is provided between one of a pair of inlet/outlet passages and one of the reservoir passages.
  • the directional control valve comprises a sub-reservoir provided between one of a pair of inlet/outlet passages and one of a pair of reservoir passages.
  • the plunger When the plunger is moved from the inlet/outlet aperture side to the outlet aperture side, the fluid is transmitted from the inlet/outlet passage to the sub-reservoir.
  • a drop speed of a load is determined by its weight upon the drop operation of the load.
  • an amount of the fluid in a head side chamber of a hydraulic cylinder is decreased, i.e., negative pressure occurs in the head side chamber of the hydraulic cylinder, the fluid transmitted from the inlet/outlet port enters into the sub-reservoir.
  • a check valve is opened so that a short flow of the fluid is compensated by supplying the fluid on the outlet side from the sub-reservoir through a supply passage and the other inlet/outlet passage to the head side chamber of the hydraulic cylinder.
  • the check valve is closed so that the fluid in the sub-reservoir is transmitted through the back pressure valve to the reservoir passage.
  • FIG. 1 is a sectional view of a directional control valve according to a first embodiment of the present invention.
  • FIG. 2 is a sectional view of a directional control valve according to a second embodiment of the present invention.
  • FIG. 3 is a sectional view of a directional control valve according to a third embodiment of the present invention.
  • FIG. 4(a) is a sectional view of a conventional directional control valve with a regeneration path according to Japanese Patent Publication No. 46-15059.
  • FIG. 4(b) is a sectional view of a conventional directional control valve with a regeneration path according to Japanese Patent Publication No. 41-10446.
  • FIG. 5(a) is a diagram of a hydraulic circuit for a conventional directional control valve which is provided with an exhausted fluid throttling device containing a check valve, in the outside position of a housing so as to perform an exhausted fluid throttling function.
  • FIG. 5(b) is a partial diagram of a plunger having a metering notch which is used for a conventional directional control valve with an exhausted fluid throttling function.
  • FIG. 6 is a diagram of a hydraulic circuit for a hydraulic shovel.
  • a plunger 12 is slidably inserted into a bore of a casing 10.
  • the casing 10 there are formed a pair of inlet/outlet passages 14 and 16, inlet/outlet apertures 17 and 19 connected to the inlet/outlet passages, an inverted U-shaped supply passage 18 arranged between the inlet/outlet passages, and reservoir passages 20 and 22 respectively arranged on the outside of the inlet/outlet passages and connected to a reservoir 23.
  • a primary bypass passage 24 is connected through a check valve 27 to a central portion of the U-shaped supply passage 18 and communicates with a pump 25.
  • a pair of secondary bypass passages 21 and 26 are respectively arranged between the U-shaped supply passage 18 and the bypass passage 24 and communicates with a reservoir 23.
  • fluid pumped from the pump 25 is circulated to the reservoir 23 when the plunger 12 is placed in a neutral position.
  • the fluid is delivered to the U-shaped supply passage 18 through the bypass passage 24 and the check valve 27.
  • a sub-reservoir 28 provided between the inlet/outlet aperture 19 and the reservoir passage 22 is connected on one side through a check valve 30 to the U-shaped supply passage 18 and on the other side through a back pressure valve 32 to the reservoir passage 22.
  • Generally known actuator protecting members 34 and 36 are respectively arranged between the inlet/outlet passages 14 and 16 and the reservoir passages 20 and 22.
  • Each of the inlet/outlet apertures 17 and 19 is connected to a hydraulic cylinder 70 so as to raise or lower a load "W" by transmitting a fluid pressure to the cylinder.
  • the directional control valve having the above-mentioned structure operates as follows:
  • a regeneration path according to this invention is operated such that the shortage of the fluid amount in the head-side chamber can be compensated by transmitting the fluid, which is exhausted from a rod side chamber 70b, through the inlet/outlet aperture 19 and the sub-reservoir 28 to the reservoir 23.
  • the check valve 30 is opened so that the shortage of the fluid is compensated by supplying the fluid from the
  • FIG. 2 is a sectional view of the directional control valve according to second embodiment, which comprises a check valve 38 in the plunger.
  • the directional control valve can perform a regeneration check function without a combination of multiple check valves so as to obtain enough passage-forming area and sufficient strength of the plunger.
  • a throttle valve 40 is screwed between a sub-reservoir 28 and a reservoir passage 22 in the casing 10 in order to reduce the speed as descent of a piston which is determined by a load "W".
  • the speed of descent can be changed by replacing the throttle valve to be used as the minimum part.
  • the throttle valve is capable of being easily controlled by any means, for example, the plunger of a spring-float type may be provided in the throttle valve so that area of an aperture 42 can be controlled by a backward/forward motion of the plunger caused by a revolving motion of the throttle valve.
  • a back pressure is generated in the sub-reservoir 28 by using the back pressure valve 32.
  • any other means such as a throttle valve or a controllable throttle valve, etc. may be employed instead of the back pressure valve.
  • a directional control valve in combination with a casing containing a bore, a pair of inlet/outlet passages, a supply passage formed between the inlet/outlet passages, a pair of reservoir passages formed on the outside of the respective inlet/outlet passages and a reciprocable plunger capable of opening and closing the respective passages, such that fluid is supplied and exhausted from inlet/outlet apertures connected to the inlet/outlet passages according to a movement of the plunger.
  • the directional control valve is also provided with a sub-reservoir between one of a pair of the inlet/outlet passages and one of the reservoir passages such that exhausted fluid is transmitted from the sub-reservoir to the inlet/outlet passage when moving the plunger from the inlet/outlet aperture side to the outlet aperture side.
  • the sufficient strength of the plunger and enough space for the passages to be formed in the plunger can be obtained.
  • the regeneration path is formed without eliminating the function of a negative pressure preventing valve in case of placing the plunger in the neutral position.
  • the minimum number of parts can perform exhaust fluid throttling functions, resulting in a simple inner structure of the plunger and the casing, etc. Therefore, parts manufacture and assembly adjustment are facilitated so that manufacturing cost can be efficiently reduced.
  • each sub-reservoir in the preferred embodiments can be operated effectively.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Multiple-Way Valves (AREA)
  • Fluid-Pressure Circuits (AREA)
US07/469,187 1989-01-27 1990-01-24 Directional control valve Expired - Lifetime US5022434A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1-7659[U] 1989-01-27
JP1989007659U JPH0716943Y2 (ja) 1989-01-27 1989-01-27 方向制御弁

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US5022434A true US5022434A (en) 1991-06-11

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Application Number Title Priority Date Filing Date
US07/469,187 Expired - Lifetime US5022434A (en) 1989-01-27 1990-01-24 Directional control valve

Country Status (3)

Country Link
US (1) US5022434A (enrdf_load_stackoverflow)
JP (1) JPH0716943Y2 (enrdf_load_stackoverflow)
KR (1) KR0155989B1 (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5394903A (en) * 1990-03-05 1995-03-07 Komatsu Zenoah Kabushiki Kaisha Hydraulic control valve
US5540258A (en) * 1994-09-30 1996-07-30 Samsung Heavy Industries Co., Ltd. Holding check control valve
US5673605A (en) * 1994-09-30 1997-10-07 Samsung Heavy Industries Co. Ltd. Motor cavitation prevention device for hydraulic systems
US5832808A (en) * 1994-08-05 1998-11-10 Komatsu Ltd. Directional control valve unit
DE19727881A1 (de) * 1997-06-30 1999-01-07 Rexroth Mannesmann Gmbh Hydraulisches Wegeventil mit Druckkompensation nach dem Mengenteilerprinzip
US5996623A (en) * 1995-05-15 1999-12-07 Nordwin Ab Hydraulic directional-control valve
US6116143A (en) * 1996-07-05 2000-09-12 Parker Hannifin Gmbh Controller for a fluid cylinder
US20030000373A1 (en) * 2000-02-04 2003-01-02 Jurgen Weber Method and device for controlling a lift cylinder, especially of working machines
US20060191582A1 (en) * 2003-06-04 2006-08-31 Bosch Rexroth Ag Hydraulic control arrangement
US20090217983A1 (en) * 2006-03-14 2009-09-03 Robert Bosch Gmbh Hydraulic valve assembly
US20120211101A1 (en) * 2011-02-18 2012-08-23 Gerd Scheffel Hydraulic control valve for a one-sided operating differential cylinder having five control edges
US9810243B2 (en) 2012-08-15 2017-11-07 Kyb Corporation Switching valve

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101506744B1 (ko) * 2008-12-24 2015-03-30 두산인프라코어 주식회사 건설기계의 재생밸브 조립체
KR100910387B1 (ko) * 2009-02-04 2009-08-04 이텍산업 주식회사 제설날 지면접촉 과부하 방지장치
KR100912597B1 (ko) * 2009-05-13 2009-08-19 신우공업 주식회사 유체제어밸브의 병렬식 복합제어 밸브바디

Citations (5)

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Publication number Priority date Publication date Assignee Title
US2448557A (en) * 1946-10-21 1948-09-07 Hydraulic Control Engineering Control valve with operating position hold
US2651324A (en) * 1949-11-01 1953-09-08 New York Air Brake Co Multiple control valve
US2916050A (en) * 1958-09-17 1959-12-08 New York Air Brake Co Four position control valve having a float position
US2949097A (en) * 1957-12-11 1960-08-16 New York Air Brake Co Five position control valve having power float position
US2980136A (en) * 1959-06-25 1961-04-18 Cessna Aircraft Co Hydraulic flow control system and valve with anti-cavitation feature

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GB1422939A (en) * 1972-01-14 1976-01-28 Sperry Rand Ltd Hydraulic valves
FR2593265B1 (fr) * 1986-01-17 1988-04-22 Rexroth Sigma Distributeur de fluide hydraulique sous pression
JPH02134401A (ja) * 1988-11-10 1990-05-23 Diesel Kiki Co Ltd 油圧制御装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2448557A (en) * 1946-10-21 1948-09-07 Hydraulic Control Engineering Control valve with operating position hold
US2651324A (en) * 1949-11-01 1953-09-08 New York Air Brake Co Multiple control valve
US2949097A (en) * 1957-12-11 1960-08-16 New York Air Brake Co Five position control valve having power float position
US2916050A (en) * 1958-09-17 1959-12-08 New York Air Brake Co Four position control valve having a float position
US2980136A (en) * 1959-06-25 1961-04-18 Cessna Aircraft Co Hydraulic flow control system and valve with anti-cavitation feature

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5394903A (en) * 1990-03-05 1995-03-07 Komatsu Zenoah Kabushiki Kaisha Hydraulic control valve
US5832808A (en) * 1994-08-05 1998-11-10 Komatsu Ltd. Directional control valve unit
US5540258A (en) * 1994-09-30 1996-07-30 Samsung Heavy Industries Co., Ltd. Holding check control valve
US5673605A (en) * 1994-09-30 1997-10-07 Samsung Heavy Industries Co. Ltd. Motor cavitation prevention device for hydraulic systems
US5996623A (en) * 1995-05-15 1999-12-07 Nordwin Ab Hydraulic directional-control valve
US6116143A (en) * 1996-07-05 2000-09-12 Parker Hannifin Gmbh Controller for a fluid cylinder
DE19727881A1 (de) * 1997-06-30 1999-01-07 Rexroth Mannesmann Gmbh Hydraulisches Wegeventil mit Druckkompensation nach dem Mengenteilerprinzip
US6701823B2 (en) * 2000-02-04 2004-03-09 O&K Orenstein & Koppel Aktiengesellschaft Method and device for controlling a lift cylinder, especially of working machines
US20030000373A1 (en) * 2000-02-04 2003-01-02 Jurgen Weber Method and device for controlling a lift cylinder, especially of working machines
US20060191582A1 (en) * 2003-06-04 2006-08-31 Bosch Rexroth Ag Hydraulic control arrangement
US7628174B2 (en) * 2003-06-04 2009-12-08 Bosch Rexroth Ag Hydraulic control arrangement
US20090217983A1 (en) * 2006-03-14 2009-09-03 Robert Bosch Gmbh Hydraulic valve assembly
US20120211101A1 (en) * 2011-02-18 2012-08-23 Gerd Scheffel Hydraulic control valve for a one-sided operating differential cylinder having five control edges
US9273664B2 (en) * 2011-02-18 2016-03-01 Parker Hannifin Corporation Hydraulic control valve for a one-sided operating differential cylinder having five control edges
US9810243B2 (en) 2012-08-15 2017-11-07 Kyb Corporation Switching valve
DE112013002580B4 (de) 2012-08-15 2024-12-05 Kyb Corporation Schaltventil

Also Published As

Publication number Publication date
KR0155989B1 (ko) 1999-02-18
JPH0716943Y2 (ja) 1995-04-19
JPH02101179U (enrdf_load_stackoverflow) 1990-08-13
KR900012028A (ko) 1990-08-02

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